The invention relates to a laser process apparatus for creating a shaped heating pattern on a workpiece. More particularly, it relates to a laser soldering system having a programmable laser beam angle of incidence while maintaining a constant path length and having a programmable laser beam heating pattern.
A laser process system available in the prior art such as one used for soldering typically involves a simple focusing of the laser energy into a specific spatial distribution on a solder joint and adjusting the power level and duration to melt the solder so that the normal process of reflow and resolidification can occur. Mirrors are used to bend or move the laser beam and XY tables are used to move a workpiece. If the angle of incidence of the laser beam is changed to avoid obscuration of a solder site, then the laser beam pathlength changes requiring adjustments be made to the laser beam spot size by refocusing. If the angle of incidence cannot be varied, then a particular component being soldered may have to be repositioned requiring additional time and effort. In addition, if a coaxial TV image of the workpiece and the laser beam spot on the workpiece is being observed, changing of the path length requires reimaging of the TV view.
Components to be soldered have various shaped terminals although the most common solder joint shapes for soldering such terminals comprise a line and an annulus. Laser beams have been shaped to achieve desired heating patterns by many different optical techniques which often result in power loss through the optics or the techniques are not suitable for production environment use due to time consuming adjustments or geometrical limitations.